Role of STARD4 in sterol transport between the endocytic recycling compartment and the plasma membrane
Bibliographic record
Abstract
Cholesterol is an essential constituent of membranes in mammalian cells. The plasma membrane and the endocytic recycling compartment (ERC) are both highly enriched in cholesterol. The abundance and distribution of cholesterol among organelles are tightly controlled by a combination of mechanisms involving vesicular and nonvesicular sterol transport processes. Using the fluorescent cholesterol analogue dehydroergosterol, we examined sterol transport between the plasma membrane and the ERC using fluorescence recovery after photobleaching and a novel sterol efflux assay. We found that sterol transport between these organelles in a U2OS cell line has a t 1/2 =12–15 min. Approximately 70% of sterol transport is ATP independent and therefore is nonvesicular. Increasing cellular cholesterol levels dramatically increases bidirectional transport rate constants, but decreases in cholesterol levels have only a modest effect. A soluble sterol transport protein, STARD4, accounts for ∼25% of total sterol transport and ∼33% of nonvesicular sterol transport between the plasma membrane and ERC. This study shows that nonvesicular sterol transport mechanisms and STARD4 in particular account for a large fraction of sterol transport between the plasma membrane and the ERC.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".